In the article I thought it said they monitored the brain for any activity in response to the shock and the neurons that activated were assumed to be the associated in response to the memory. This is a far cry from being able to look at a neuron in situ and saying what memory or memories are associated with that neuron.

This is an old article and may be superceded by more recent research but false memories may not have to be implanted, in some sense we do it ourselves every time we recall a memory http://www.smithsonianmag.com/science-nature/how-our-brains-...